In order to derive the differential identities mentioned above, one has to find recurrence relations and prove a Christoffel–Darboux formula for the polynomials (REF ) and follow a path similar to that introduced by I. Krasovsky in [1]}. Note that the recurrence relations can be found by analyzing the function \(\mathcal {M}(z;n):= \mathcal {X}(z;n+1)\mathcal {X}^{-1}(z;n)\) , which is holomorphic in \(\lbrace 0\rbrace \)  and can be globally determined by its singular parts at zero and infinity.
